Method of utilizing resources efficiently in a reverse link transmission

ABSTRACT

A method of transmitting data by at least one access terminal (AT) in a wireless communication system is disclosed. More specifically, the method includes ceasing all transmissions by the at least one AT during a duration corresponding to a duration used by an access node (AN) to transmit a superframe preamble, wherein the superframe comprises a plurality of physical frames.

This application claims the benefit of U.S. Provisional Application No.60/806,761, filed on Jul. 7, 2006, and U.S. Provisional Application No.60/863,935, filed on Nov. 1, 2006, which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of utilizing resources, andmore particularly, to a method of utilizing resources efficiently inreverse link transmission.

2. Discussion of the Related Art

In the world of cellular telecommunications, those skilled in the artoften use the terms 1G, 2G, and 3G. The terms refer to the generation ofthe cellular technology used. 1G refers to the first generation, 2G tothe second generation, and 3G to the third generation.

1G refers to the analog phone system, known as an AMPS (Advanced MobilePhone Service) phone systems. 2G is commonly used to refer to thedigital cellular systems that are prevalent throughout the world, andinclude CDMAOne, Global System for Mobile communications (GSM), and TimeDivision Multiple Access (TDMA). 2G systems can support a greater numberof users in a dense area than can 1G systems.

3G commonly refers to the digital cellular systems currently beingdeployed. These 3 G communication systems are conceptually similar toeach other with some significant differences.

In today's wireless communication system, a user (or a mobile) canfreely roam about while enjoying uninterrupted service. As such, it isimportant to improve upon current wireless communication technology toenhance the user's way of life in terms of wireless communicationtechnology. To this end, better schemes and techniques can be devised soas to improve efficiency as well as effectiveness of service of acommunication system under the all sorts of different conditions andenvironments of the wireless system. To address various conditions andenvironments and to enhance communication service, various methods,including more efficient utilization of wireless resources, in bothforward link and reverse link, can be implemented to promote moreeffective and efficient transmission.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method of utilizingresources efficiently in reverse link transmission that substantiallyobviates one or more problems due to limitations and disadvantages ofthe related art.

An object of the present invention is to provide a method oftransmitting data by at least one access terminal (AT) in a wirelesscommunication system.

Another object of the present invention is to provide a method ofmeasuring data for load control by an access node (AN) in a wirelesscommunication system

A further object of the present invention is to provide a structure of asuperframe.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, amethod of transmitting data by at least one access terminal (AT) in awireless communication system includes ceasing all transmissions by theat least one AT during a duration corresponding to a duration used by anaccess node (AN) to transmit a superframe preamble, wherein thesuperframe comprises a plurality of physical frames.

In another aspect of the present invention, a method of measuring datafor load control by an access node (AN) in a wireless communicationsystem includes measuring noise variance during a duration in which alltransmissions from at least one access terminal (AT) is ceased and theduration corresponds to a duration used by the AN to transmit asuperframe preamble, wherein the superframe comprises a plurality ofphysical frames.

In a further aspect of the present invention, a structure of asuperframe includes a plurality of reverse link (RL) physical frameswhich correspond to a plurality of forward link (FL) physical frames anda preamble, wherein a first part of a RL physical frame corresponding tothe FL preamble is devoid of data and a second part of RL physicalframes corresponding to other FL physical frames are occupied with data.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings;

FIG. 1 is an exemplary diagram illustrating a structure of a superframein which a first physical frame is repeated or elongated;

FIG. 2 is another exemplary diagram illustrating a structure of asuperframe in which first physical frame is repeated or elongated;

FIG. 3 is an exemplary diagram illustrating utilization of RL resourcesin the superframe; and

FIG. 4 is another exemplary diagram illustrating utilization of RLresources in the superframe.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

Typically, an access terminal (AT) receives permission from an accessnetwork (AN) before transmitting data. This operation can be referred toas scheduling. In order to schedule for transmission or receivepermission from the AN, the AT can request for permission with suchinformation as amount of data it has in the buffer, power headroom, etc.This request can be transmitted to the AN at any time. That is the ATcan transmit the request whenever necessary and/or at a predeterminedtime. After the scheduling is completed, the AT can then transmit datato the AN.

With respect to data transmission in a wireless communication system, anunit of transmission can be defined by a specified number of physicalframes and a preamble. This can be referred to as a superframe. Thetransmission unit is applicable to both a forward link (FL) and reverselink (RL) transmission. Superframe preamble is mainly for FLtransmission but does not preclude RL transmission.

The transmission unit or the superframe comprises 24 or 25 physicalframes and a preamble. Each physical frame includes a plurality oforthogonal frequency division multiplexing (OFDM) symbols. For example,the physical frame comprises eight (8) symbols (e.g., 8×113.93 μs (6.51μs CP)=911.44 μs). Each OFDM symbol duration is 113.93 μs including 6.51μs cyclic prefix. Moreover, the preamble includes 8 OFDM symbols.

The superframe typically starts with the preamble in the FL, mainly toprovide synchronization. The superframe is also used to carrynetwork-specific and sector-specific information. Because the AT needsto know the start of the reference timing so that the RL transmissioncan be synchronized with the FL transmission. In other words, the RLtransmission can be aligned with the FL transmission (e.g., samesuperframe duration) for efficient transmission.

Generally, the superframe preamble can carry packet control information,packet data, and a paging channel, and these can be transmittedperiodically in the superframe preamble. More specifically, the preamblecarries broadcast channels. The first five (5) OFDM symbols carry fastpacket broadcast control channel (F-PBCCH) and fast secondary broadcastcontrol channel (F-SBCCH) in even superframes, and the F-PBCCH and fastquick paging channel (F-QPCH) in odd superframes.

Further, the preamble can be identified based on time and frequency andfurther identified by sector specific sequences. That is, the preamblecan include time division multiplexing (TDM) pilots, code divisionmultiplexing (CDM) pilots, and/or sector-specific sequence.

For example, the preamble can include TDM pilots (e.g., TDM 1, TDM 2,and TDM 3). TDM 1 carries sector specific information and/or generalizedchirp-like (CCL) sequence for time/frequency synchronization. TDM 2 andTDM 3 are sector-specific sequences (e.g., Walsh sequences). Inaddition, other sector interference channel (OSICH) can be transmittedas a differential phase between TDM 2 and TDM 3 (e.g., 0, 2π/3, −2π/3).

In general, the physical frames of the superframe contain data, controlinformation, and dedicated pilot, among others. The physical frames areoften preceded by a preamble. The preamble is designed to supportsynchronization (time and frequency) and to transmit system parameters,overhead messages, and so on, in the FL. Lastly, the durations of thesuperframe for the FL and the RL are the same.

A FL transmission is a transmission made from the AN to an accessterminal (AT). On the contrary, a RL transmission is a transmission madefrom AT to an AN. Typically, the RL transmission includes transmissionmade from multiple sources (e.g., ATs) to a single destination (e.g.,AN).

Due to the nature of RL transmissions, which includes transmission frommultiples sources to a single destination, the transmission of physicalframes is not preceded by a preamble. Furthermore, due the superframesin the FL and RL having the same durations, the transmission may be lessefficient.

To address this lack of preamble and the durational issue, thesuperframe can be modified. More specifically, the first physical framecan be repeated or put differently, the first physical frame can beelongated, so as to maintain the same durations of superframe in the FLand RL. FIG. 1 is an exemplary diagram illustrating a structure of asuperframe in which a first physical frame in RL is repeated orelongated.

Referring to FIG. 1, the first physical frame of the AT, which relatesto the transmission in the RL, is repeated (or elongated). Comparing tothe first physical frame of AN, the first physical frame of the AT islonger (e.g., twice) than that of the AN. That is, the first RL physicalframe is elongated to align with the preamble and the first physicalframe of the FL so that the FL and the RL transmissions can besynchronized.

FIG. 2 is another exemplary diagram illustrating a structure of asuperframe in which first physical frame is repeated or elongated. Thedescription of FIG. 2 is similar to that of FIG. 1.

Referring to the descriptions with respect to FIGS. 1 and 2 regardingrepeated or elongated first physical frame, the resources (e.g.,frequency bandwidth and time) can be considered to be utilizedinefficiently. As such, the physical frames can be considered to beprotected differently.

Therefore, instead of repeating or elongating the first physical framein the RL, the duration of the first RL frame can be modified tocorrespond to the duration of the FL preamble. Hereinafter, this RLframe can be referred to as the RL portion.

In the transmission to the AN, the RL portion (or the redundant part)can include the requests for RL transmissions from the ATs, feedbackinformation including absolute values of channel quality feedbacks fromthe ATs, and/or periodic silent moment or silent period (e.g., null) tohelp the AN measure noise variance. As described above, the requests canrefer to scheduling and receiving permission from the AN. Furthermore,the channel quality feedback can relate to multi-input, multi-output(MIMO) channels, beamforming, and/or sub-band(s).

The measured noise variance can be used to control the reverse link loadthrough interference-over-thermal (IoT) or rise-over-thermal (RoT).Moreover, the requests and the feedback information (e.g., absolutechannel quality feedback transmissions) share the resources with datatransmission in physical frames. Using this approach of requestreallocation and absolute channel quality feedback transmissions, theavailable resources for data transmission can be increased.

FIG. 3 is an exemplary diagram illustrating utilization of RL resourcesin the superframe. In FIG. 3, the RL portion of the superframe, whichcorresponds to the preamble portion of the FL superframe, can includerequest(s), feedback information (e.g., channel quality information(CQI)), and silent moment/period. As illustrated, the duration of the RLportion corresponds to the duration of the preamble portion of the FL.Furthermore, the duration of the preamble portion of the FL can be thesame as the duration of one FL physical frame.

In comparison to FIGS. 1 and 2 in which the first frame (e.g., RLportion) is elongated and does not correspond to the superframe preambleof the FL, the RL portion, as illustrated in FIG. 3, is configured tocorrespond to the duration of the preamble. As a result, the resourcescan be used more efficiently.

Alternatively, the RL portion corresponding to the duration of the FLsuperframe preamble can be divided into the duration of the physicalframe and the remaining duration. In other words, the preamble durationis equal to the duration of the physical frame plus the remainingduration. The duration of the RL portion can vary based on the durationof the physical frame.

As discussed, the remaining duration can be used to transmit therequests from the AT(s), feedback information including absolute valuesof channel quality feedbacks from the ATs, and/or periodic silentmoment/period to help the AN measure noise variance.

Alternatively, the preamble duration can be equal to the duration of thephysical frame. Here, the remaining duration is not necessary since thepreamble duration and the duration of the physical frame are equal.

FIG. 4 is another exemplary diagram illustrating utilization of RLresources in the superframe. In FIG. 4, the RL portion can be used totransmit the requests from the AT(s), feedback information, and/orsilent moment/period. Depending on the amount of data to transmit in theRL, the duration of the AT can vary. That is, the duration of the RL (orthe RL portion) may be shorter than the duration of the superframepreamble of the FL. As illustrated, the duration of the RL portion canbe half of that of the superframe preamble. Moreover, this RL portioncan be placed in the front half or back half relative to thecorresponding superframe preamble of the FL. Referring to FIG. 4, the RLportion is placed in the back half with respect to the preamble, but itcan be placed in the front half as well.

Alternatively, the duration of the RL portion can be equal to theduration of the superframe preamble. That is, the duration can be eight(8) symbols when RL is shorter than the duration of the superframepreamble as illustrated in FIG. 4 or the duration of the RL portion canbe 16 symbols which correspond to the duration of the superframepreamble. In fact, the duration of the RL portion can be eight (8) aswell as multiples of eight (8) (e.g., 16, 24, and so on).

The silent moment/period can be total or partial with respect to theresources silenced. In the case of total silence period, nothing istransmitted over the entire bandwidth during the predefined duration(e.g., remaining duration). The silent moment/period can be a periodduring which null signals are transmitted to the AN from all ATs. Here,null signals transmission means that no signals are transmitted to theAN from all ATs.

Furthermore, some frequency bandwidths (sub-bands or collection ofsub-carriers) can be silenced, in the case of partial silencemoment/period during the predefined duration.

For example, referring to FIG. 4, a physical frame (e.g., PHY#0) and theRL portion combined correspond to the preamble duration. After the PHY#0is transmitted, the silence period follows during which nothing (or nullsignals) is transmitted. Furthermore, instead of sending nothing (ornull signals), requests and/or channel quality feedback can betransmitted.

From the AT's perspective, transmission to the AN can be controlled.That is, the RL transmission can be ceased periodically. The AT candecide to periodically cease its transmission based on factors such aschannel condition. Furthermore, the AT can periodically cease itstransmission based on a command from the AN. The AT can be informed ofperiodic ceasing by a system parameter.

Further, normal transmission of data and/or control channels (orsegments) can occur in the duration of physical frame not used in thetransmission of the silent moment/period. For example, reverse linkacknowledgement channel (R-ACKCH) and/or reverse link data channel(R-DCH) and/or reverse link code division multiple access (CDMA) controlsegment can be transmitted in the portion of the “long” frame which isnot silenced. Here, the data channel includes any format of transmissionincluding OFDM, CDMA, etc.

It will be apparent to those skilled in the art that variousmodifications and variations will be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A method of transmitting data by at least one access terminal (AT) ina wireless communication system, the method comprising ceasing alltransmissions by the at least one AT during a duration corresponding toa duration used by an access node (AN) to transmit a superframepreamble, wherein the superframe comprises a plurality of physicalframes.
 2. The method of claim 1, wherein each of the plurality ofphysical frames comprises a plurality of orthogonal frequency divisionmultiplexing (OFDM) symbols.
 3. The method of claim 1, wherein thetransmission is ceased periodically.
 4. The method of claim 3, whereinthe periodic ceasing of the transmission is informed by a systemparameter.
 5. The method of claim 1, further comprising transmitting arequest message from the AT during the duration corresponding to theduration used by the AN to transmit the superframe preamble.
 6. Themethod of claim 1, further comprising transmitting a channel qualityfeedback from the AT during the duration corresponding to the durationused by the AN to transmit the superframe preamble.
 7. The method ofclaim 1, further comprising transmitting a multi input, multi output(MIMO) channel quality feedback from the AT during the durationcorresponding to the duration used by the AN to transmit the superframepreamble.
 8. The method of claim 1, further comprising transmitting abeamforming channel quality feedback from the AT during the durationcorresponding to the duration used by the AN to transmit the superframepreamble.
 9. The method of claim 1, further comprising transmitting asub-band channel feedback from the AT during the duration correspondingto the duration used by the AN to transmit the superframe preamble. 10.The method of claim 1, wherein the transmissions are ceased periodicallyaccording to a command from the AN.
 11. The method of claim 1, furthercomprising transmitting any one of a reverse link acknowledgementchannel (R-ACKCH), reverse link data channel (R-DCH), or reverse linkcode division multiple access (CDMA) control segment during a durationin which transmission is not ceased.
 12. A method of measuring data forload control by an access node (AN) in a wireless communication system,the method comprising measuring noise variance during a duration inwhich all transmissions from at least one access terminal (AT) is ceasedand the duration corresponds to a duration used by the AN to transmit asuperframe preamble, wherein the superframe comprises a plurality ofphysical frames.
 13. The method of claim 12, wherein the transmission isceased periodically.
 14. The method of claim 12, further comprisingtransmitting a command to at least one AT to cease transmissionperiodically.
 15. The method of claim 12, wherein each of the pluralityof physical frames comprises a plurality of orthogonal frequencydivision multiplexing (OFDM) symbols.
 16. The method of claim 12,further comprising receiving a request message from the AT during aduration corresponding to the duration of the used by the AN to transmitthe superframe preamble.
 17. The method of claim 12, further comprisingreceiving a multi input, multi output (MIMO) channel quality feedbackfrom the AT during a duration corresponding to the duration used by theAN to transmit the superframe preamble.
 18. The method of claim 12,further comprising receiving a beamforming channel quality feedback fromthe AT during a duration corresponding to the duration used by the AN totransmit the superframe preamble.
 19. The method of claim 12, furthercomprising receiving a sub-band channel feedback from the AT during aduration corresponding to the duration used by the AN to transmit thesuperframe preamble.
 20. A structure of a superframe, comprising aplurality of reverse link (RL) physical frames which correspond to aplurality of forward link (FL) physical frames and a preamble, wherein afirst part of a RL physical frame corresponding to the FL preamble isdevoid of data and a second part of RL physical frames corresponding toother FL physical frames are occupied with data.